Adhesives free bark panels: An alternative application for a waste material

The proportion of bark in tree trunks is in the range of ~ 10-20%. This large amount of material is currently mainly considered as a by- or even waste-product by the timber processing industry. Recently, efforts towards the use of bark have been made, e.g. as a raw material to harvest different chemical compounds or as an additive for wood particle boards. Our motivation for this work was to keep the bark in an almost natural state and explore alternative processes and applications for use. The traditional method of de-barking tree trunks by peeling was used to harvest large bark pieces. Two pieces of peeled bark were placed crosswise, with the rhytidom side (outer bark) facing each other. After different conditioning steps, bark pieces were hot pressed to panels without adding adhesives. These experiments on bark samples of different Central European tree species suggest that production of panels with species dependent properties is possible and feasible. This is a step towards producing sustainable panels by using a natural waste material, while retaining its beneficial structure and its natural chemical composition.

Advanced materials design based on waste wood and bark

Trees belong to the largest living organisms on Earth and plants in general are one of our main renewable resources. Wood as a material has been used since the beginning of humankind. Today, forestry still provides raw materials for a variety of applications, for example in the building industry, in paper manufacturing and for various wood products. However, many parts of the tree, such as reaction wood, branches and bark are often discarded as forestry residues and waste wood, used as additives in composite materials or burned for energy production. More advanced uses of bark include the extraction of chemical substances for glues, food additives or healthcare, as well as the transformation to advanced carbon materials. Here, we argue that a proper understanding of the internal fibrous structure and the resulting mechanical behaviour of these forest residues allows for the design of materials with greatly varying properties and applications. We show that simple and cheap treatments can give tree bark a leather-like appearance that can be used for the construction of shelters and even the fabrication of woven textiles. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.

Hydrocephalus after subarachnoid bleeding. A correlation of clinical findings, the results of radioisotope Cisternography and computer-assisted tomography

Out of a group of patients suffering from a spontaneous subarachnoid hemorrhage 27 patients were checked by computer-assisted tomography (CAT), 23 patients by radioisotope cisternography, and 21 patients by both diagnostic procedures. The results were correlated with the clinical observations. The flow of the CSF was normal in 7 patients (30.43%), and pathological in 16 patients (69.56%). Of the 27 patients checked by CAT, 23 (85.18%) showed a ventricular dilatation, which in 17 patients (62.96%) was not connected with a corresponding increase of the cisterns of the convexity. The clinical symptoms of hydrocephalus, the degree of impairment of the circulation of the CSF determined by radioisotope cisternography and the ventricular diameter as determined by CAT correlated well.

[Acute paraplegia due to embolism from nucleus pulposus tissue (author's transl)]

Typical anterior spinal artery syndrome with initially severe pain and paraplegia with sensory disturbances occurred after a fall in a 36-year-old man with a history of lumbago. Multiple emboli of fibrocartilaginous material with nucleus pulposus cells were found in the foci of myelomalacia. The embolism of nucleus pulposus tissue originating from Schmorl's nodules was probably carried via the blood vessels of the neighbouring vertebral bodies with retrograde flow through the perispinal venous plexus into spinal cord veins and hence into the arteries of the spinal cord via veno-arterial anastomoses. A transitory increase in intra-abdominal pressure was probably the cause of the inversion of venous flow.

[Chronic lymphocytic meningitis with polytopic involvement of the nervous system (after tick bite?)]

After an introductory description of the terminology, the individual experiences of 65 patients with chronic lymphocytic radicular myelo-meningitis after tick bite are reported with reference to the literature. The finding of the cerebrospinal fluid in the lymphoplasmocytic meningitis together with radicular and regional pains, and a one-or two-sided peripheral facial nerve paresis represents the nucleus syndrome of the illness, which usually progresses as meningopolyneuritis. The pathogen, probably a virus, could not yet be isolated. The treatment is purely symptomatical with corticosteroids and antibiotics. Quoad vitam, the prognosis is invariably favourable, residues are frequent.

[Myelographic findings in multiple sclerosis in combination with cervical spondylosis]

Differential diagnostic problems are considered in 8 patients suffering from multiple sclerosis and cervical spondylosis simultaneously. When a clinical suspicion for multiple sclerosis is combined with a relatively normal sagittal diameter of the cervical vertebral canal, myelographic findings due to cervical spondylosis must be evaluated carefully.